1. Field of the Invention
The present invention relates generally to image processing executed in an autofocus camera, etc., and more particularly, to an image processing apparatus, an image processing method, and an image processing program that allow visual recognition of focusing operation through an image.
2. Description of the Related Art
In autofocusing (AF) operation carried out in a camera, a digital camera, etc., incorporated into a cellular phone, a portable information terminal unit (PDA: Personal Digital Assistance), etc., a lens moving mechanism is driven by a motor to move a lens physically to change its position and look for a focusing position, so that the lens is fixed at an optimum focusing position. As this focusing operation proceeds, an image formed on an image-capturing element is displayed on a monitor screen. This allows a user to visually recognize the state of image changed by the focusing operation from the monitor screen.
A focusing device disclosed in a parent document 1 shown below presents a technique related to such display of an image in a state of focusing. The focusing device forms an image according to a state of focusing by recognizing a state of focusing based on contrast information on a photographed subject and changing the frequency characteristics of an aperture compensating circuit in a processing unit.
A solid image-capturing device disclosed in a patent document 2 shown below reads image output being in focus and that being blurred separately out of a solid image-capturing element, and obtains a brightness signal from the output in focus and a color signal from the output blurred, thus offers an image of a high resolution without moiré.
A camera disclosed in a patent document 3 shown below determines a depth of field from a condition given upon photographing, and reduces the level of the edge of an image signal in a nonfocusing area, which cannot be covered by the depth of field, out of image signals read out of an image-capturing device, thus displays a state of blur in photographing on an electronic finder.
Patent document 1: Japanese Patent Application Laid-Open Publication No. 1993-183796
Patent document 2: Japanese Patent Application Laid-Open Publication No. 1987-173876
Patent document 3: Japanese Patent Application Laid-Open Publication No. 1991-260638
A cellular phone, PDA, etc., is equipped with a pan focus camera, which has a small lens and offers a greater depth of field. Executing pan focusing, this type of camera shows a user less variation in an image on a monitor screen even when a lens moves to a focusing position as a result of AF operation. Less variation in an image gives the user no sense of the completion of focusing, causing the user to feel that something is missing. This problem is not dealt with in the patent documents 1, 2, 3, and cannot be solved by considering the technical contents disclosed in the patent documents 1, 2, 3.